Campbell climate

Campbell Frost Dates and Growing Season

NOAA 1991-2020 normals for Los Gatos, 6.2 km from Campbell, elevation 365 ft

Frost and the growing season

NOAA's 1991-2020 freeze probabilities for Los Gatos. A median date has an even chance of a later freeze in spring, or an earlier one in fall.

The last spring freeze typically comes around February 2 and the first fall freeze around December 6, a growing season of about 310 days.

Median at 36°F
last March 20, first November 20
Median at 32°F
last February 2, first December 6
Median at 28°F
last January 1, first December 19

Last freeze in spring

The chance of a later freeze than the date shown. At 10 percent, one spring in ten still freezes after the date; planting after the 10 percent date for 32°F is the cautious choice.

Threshold10%20%30%40%50%60%70%80%90%
36°FApr 16Apr 8Apr 2Mar 28Mar 20Mar 13Mar 8Mar 1Feb 16
32°FMar 14Feb 28Feb 17Feb 9Feb 2Jan 27Jan 19Jan 9Dec 31
28°FJan 26Jan 17Jan 11Jan 5Jan 1Dec 30Dec 25Dec 19Dec 9
24°FJan 11Jan 4Jan 1Dec 31Dec 30Dec 26Dec 20Dec 10Dec 1
20°F–––––––––
16°F–––––––––

First freeze in fall

The chance of an earlier freeze than the date shown. At 10 percent, one fall in ten freezes before the date.

Threshold10%20%30%40%50%60%70%80%90%
36°FNov 4Nov 9Nov 12Nov 16Nov 20Nov 23Nov 26Dec 1Dec 5
32°FNov 16Nov 24Nov 28Dec 2Dec 6Dec 11Dec 16Dec 26Jan 7
28°FNov 28Dec 3Dec 10Dec 14Dec 19Dec 24Dec 30Jan 3Jan 13
24°FDec 1Dec 7Dec 16Dec 24Dec 27Dec 30Jan 1Jan 2Jan 8
20°F–––––––––
16°F–––––––––

Growing season length

Days between the last spring and first fall freeze at each threshold, with the chance of a season at least that long.

Threshold10%20%30%40%50%60%70%80%90%
36°F280267258249241235228220208
32°F346335326318310303291279263
28°F365365365364356350343336327
24°F365365365365365365365365364
20°F365365365365365365365365365
16°F365365365365365365365365365

How often it gets that cold

The share of years with at least one night at or below each temperature.

36°F or colder
100% of years
32°F or colder
97% of years
28°F or colder
58% of years
24°F or colder
12% of years
20°F or colder
0% of years
16°F or colder
0% of years

Degree days

A degree day is one degree of the daily mean temperature beyond a base, for one day. Heating degree days count cold (the fuel a house burns), cooling degree days heat, growing degree days the warmth a crop needs; each crop has its own base.

Heating degree days, base 65°F
2,562
Cooling degree days, base 65°F
625
Growing degree days, base 40°F
7,192
Growing degree days, base 45°F
5,405
Growing degree days, base 50°F
3,769
Growing degree days, base 55°F
2,410
Growing degree days, base 60°F
1,370

Growing degree days by month, base 50°F

Heating and cooling by month

MonthHeating DDCooling DDGrowing DD 50
January496042
February375078
March3201161
April2289234
May11738386
June3497513
July4171632
August3163625
September18115548
October11731379
November3410131
December508041

What this means

NOAA computes these from the daily lows at the station over 1991-2020, fitting the dates of each year's last and first freeze to a distribution, so a date can be stated at any level of risk. 36°F is a frost risk for tender plants on a clear, calm night, since the ground cools below the air above it; 32°F is a freeze; 28°F is a hard freeze that kills most annuals.

The station is 6.2 km from Campbell. Low ground, valleys and open fields freeze earlier and later than a town center or a hillside.

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Sources

NOAA NCEI U.S. Climate Normals, 1991-2020, annual and seasonal normals for station USC00045123 (Los Gatos). Public domain.